The present invention relates to a multistage compressor unit with a cooling device as used, for example, in motor vehicles.
From the state of the art it is known that the power of an internal combustion engine can be increased when a turbosupercharger is additionally employed. If the air charge for the internal combustion engine is compressed in the combustion chamber prior to ignition the internal power of the internal combustion engine is increased due to higher throughput of air and fuel per working cycle. By compressing a volume of air its temperature rises while the density of the compressed air decreases. Using an air charge treated in this way the power increase due to the compressed air charge is still low. For this reason it is necessary for the compressed air charge to be cooled down before entering the combustion chamber. This is usually done with the aid of an air charge cooler. In multistage compression of the air charge an intermediate cooler is arranged between a low-pressure compressor and a high-pressure compressor.
The intermediate coolers hitherto employed are of very large construction. Since in these the inlets and outlets on the compressor housing are spaced quite far apart costly connecting elements each having a long line path are used for the intermediate cooler arranged in between.
EP 1 505 274 A1 discloses an intermediate cooler for a two-stage exhaust turbosupercharger consisting of a low-pressure and a high-pressure compressor. The air charge cooler comprises a connecting channel carrying the air charge which connects the two compressors to one another and has an internal cooling insert. The intermediate cooler is connected to the engine via connecting elements. Feed and discharge openings of the flow openings are constructed in the connecting channel and connected to an air-conditioning system in the vehicle.